A couple of weeks ago Youngest Son and I were standing in the hallway. Youngest turned and started pushing the buttons on Oldest Son's door lock (we have keypad locks on the doors to keep Middle Son out). I asked him what he was doing and he said "practicing the door locks."
I was highly skeptical. I said I didn't believe him. I said I thought he was trying to get into Oldest's room. I thought he didn't want to say that because he was afraid he'd get in trouble for it. He stuck to his story. I repeated that I didn't believe him. I said it was ok for him to want to go into Oldest's room. If he'd told me he wanted to go into the room, he wouldn't get in trouble for that. Actually going in the room would get him in trouble, but not wanting to go in. Lying to me about what he was doing was a much larger problem.
He talked in circles a little, trying to stay out of trouble. Finally, I said one last time that I did not believe he was practicing, and asked him what we should do.
He looked down at the floor and said quietly "a time out."